303 British brass and headspace

[Longshot338]

.Ben started a thread about headspace and case seperation. I knew right from the title what the problem was, and why it happens. The replies were very informative, and explained quite clearly what goes on to cause this case seperation.

I have never heard of the o-ring technique before. Fantastic idea! What size of O-Ring do I need?

Seonddly, I want to start identifying incipient case seperation before it happens, and cull brass as necessary. I have purchased over 400 casings once fired from the EE here from different sources. I can observe the tell-tale ring around the case on many, in differing degrees of severity. Is there any way of determining how close the case is to seperating without splitting it? How do I select what to cull based off of visual inspection?

Also, how do I measure headspace in my rifle? I have a mint-condition 1943 Long Branch No.4 Mk.I* with a #0 bolt head. Based on the throat wear, bore condition, rifling, and overall appearence of this rifle, it has certainly never seen any action, and has had few rounds down the pipe. I suspect headspace is OK with this one, though I haven't checked. I also have a 4/45 (April 1945) ROF(F) (Fazakerly) No.5 Mk.I in nearly the same condition with a #2 Bolt head. Haven't fired it yet; don't know what its like.

I have a Hornady Headspace guage that measures from the base of the cartridge to the shoulder. This doesn't give me any indication of how close to specs the chamber is; it just allows me to set up my FL dies to bump the shoulder back minimally (0.002"). However, I have observed that my brass reloaded and fired out of my LB is longer to the shoulder than most of the brass I have purchased from other rifles, and longer than the brass from my old Maltby No.4 (now my brother's rifle). Is this an indiation that my headspace is excessive? If so, I can find a #1 bolt head and fit it in, but how do I check if it is too tight?

My brass resized for my LB won't chamber in my brother's Maltby, but will chamber in my Faz. If I have exessive headspace in the LB, I suspect the Faz needs a new bolt head too...

Also, if I set my FL dies to bump the shoulder of the case back by 0.001" or 0.002", will this give me the same benefits as neck sizing? I cannot for the life of me find a collet 303 die; believe me, I've tried everywhere I know for 2 years now. Does anyone know where I can buy one?

Alec

 

[9.3mauser]

The simplest way to check for insipient head separation is to take a paper clip, straighten it out and bend a little hook at the end. Use it as a feeler gauge, and you will be able to detect a little groove at the point where separation occurs. It also shows up as a bright ring around the case body, but shouldn't be confused with the expansion ring, which is normal. There is an older thread on this topic, with photos, try the search function, you might get lucky.

 

[cosmic]

The headspace of the rifle is moot if you are partially resizing the case. 303 normally headspaces on the rim. When a new case is fired, the shoulder is blown out substantially, and the case is stretched. The chambers are oversize to accommodate war time conditions.
By partially resizing, or neck sizing, you are facilitating having the case headspace on the shoulder, rather than the rim. This minimizes case stretch, and contributes to case longevity. I shoot several 303's, so I partially resize to my tightest chamber. this allows me to shoot my reloads in all of the rifles, rather than neck sizing and segregating brass.
The o ring trick is beneficial on the first firing as it reduces case stretch at the base of the case, where the incipient separation starts.

 

[Longshot338]

I'd like to be able to size according to my tightest chamber, but as I load for my brothers rifle, this bumps the shoulder back almost 0.011" whih is ase overworking for my LB. I set The die up every time I reload, and mark which rifle it is set for.

 

[smellie]

The whole idea behind the O-ring trick (I use pony-tail ties: cheaper) is so that you can fire anything in the rifle and then reload it TO FIT THAT RIFLE PERFECTLY BY NECK-SIZING ONLY. The cases now headspace on the SHOULDER, as with rimless ammo.

Service ammo for the .303 was VERY carefully regulated: rim thickness was .059" Min and .063" Max. Rims were BEVELLED to aid feeding. There is NO .303 commercial brass made anywhere in the WORLD which is to Military Spec. Likely Partizan is closest. I use DEFENCE INDUSTRIES brass: Canadian War 2 brass, best brass ever made for a .303. Headstamp DI Z and the Year (1942 through 1945).

Headspace on the RIFLES was controlled through CAREFUL fitting of the Bolt-heads. Min was .064", Max was .074". Worked wonderfully with good MilSpec ammo.

THERE IS NO GOOD MILSPEC AMMO ANY LONGER. I have seen commercial ammo with rims as thin as .040": automatic .023" EXCESS headspace, even in an absolute-minimum Rifle. It goes bang, separates after 1 reload. Most of it is not THAT bad but, with th O-ring trick on FIRST firing, it can ll be reused.

The KEY is SEGREGATION of your brass, by the Rifle it was fired in. In combination with th O-ring trick, this will give you brass which fits any SPECIFIC Rifle perfectly, can be reloaded up to and beyond 30 times..... and turns in Match-grade performance.... but you MUST keep it segregated. Load it with a Lee Collet Die for best performance.

Switching ammo about, all you can do is size for the smallest chamber, hope and pray.... and be ready for less-than-excellent accuracy and short case life.

Remember this point: over the years, the Army bought 10 million .303 rifles and they paid for them in GOLD, an average of just over an ounce per rifle. If you TREAT it and LOAD for it like the $2200 rifle it actually IS (by modern standards), you will get the best out of it..... and a Barrel thrown in which will outlast almost ANY modern barrel.

WORTH taking a bit of care, one would think.

Hope this helps.